1. Field of the Invention
The present invention relates to a substrate manufacturing process of printed wiring board, more particularly to joining technology of thin substrates.
2. Description of the Related Art
If sheet-like shape (plate-like shape) is employed as the shape of a thin substrate such as copper clad laminate in which copper foils are laminated on resin layer thereof, transportation of substrates having a low stiffness is more difficult as the thickness of the substrate decreases. For the reason, the thin substrates are set in a frame jig when they are carried and processed. However, the transportation with this condition is more difficult than transportation of a belt-like substrate using a roller. Particularly, unless a care is paid to handling of the substrates as well as transportation thereof, a work piece (substrate) may be seriously damaged.
If the frame-like transportation jig is used, the effective area of the work piece (substrate) is reduced by an amount corresponding to the area occupied by the transportation jig thereby reducing productivity.
As the core substrate of a built-up multi-layer wiring board, the copper clad laminate in which copper foils are laminated on resin layer is used, and as the resin layer, for example, glass epoxy resin in which epoxy is impregnated in glass cloth core material and polyimide resin are used. Because the polyimide resin can be adjusted easily to a uniform thickness, it allows copper foil to be laminated easily and thus, as the copper clad laminate, reel-like products as well as plate-like (sheet-like) products are manufactured. On the other hand, because the glass epoxy resin is difficult to form into a uniform thickness, the copper foil cannot be laminated thereon and as the copper clad laminate, the plate-like (sheet-like) product and roll-like products are manufactured. Here, JP 2002-141659 A has disclosed technology for joining together a product with another product.